Investigations in the following areas of pigment metabolism are proposed: (1) Continue efforts to crystallize and characterize the normal urinary ("urochrome") pigments. A combination of column chromatography, solvent extraction, and thin layer chromatography are used to fractionate the more than 30 pigments demonstrable. (2) Develop improved methods for the quantitative assay of these pigments in urine of normal subjects and of patients with metabolic diseases. (3) Complete double and triple isotope studies (glycine, ALA, and/or bilirubin) in human volunteers. (4) Continue studies of enzymes involved in the biosynthesis of pyrrole compounds.